// Tencent is pleased to support the open source community by making ncnn available.
//
// Copyright (C) 2017 THL A29 Limited, a Tencent company. All rights reserved.
//
// Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// https://opensource.org/licenses/BSD-3-Clause
//
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.

#ifndef LAYER_SPP_H
#define LAYER_SPP_H

#include "layer.h"

namespace ncnn {
/**
 * @brief 空间金字塔池化spatial pyramids pooling layer
 * 1、input image -> convolution layer (+activation) -> pooling layer -> full connnect layer -> out
 * 需要输入图片的尺寸要固定，才能保证full connnect layer的输入blob尺寸是固定的
 * 2、input image -> convolution layer (+activation) -> pooling layer ->  spatial pyramids pooling layer -> 
 * full connnect layer -> out
 * spatial pyramids pooling layer将不同尺寸输入图片得到的feature map转换为统一大小
 * 
 */
class SPP : public Layer
{
public:
    SPP();

    virtual int load_param(const ParamDict& pd);

    virtual int forward(const Mat& bottom_blob, Mat& top_blob, const Option& opt) const;

    enum PoolMethod
    {
        PoolMethod_MAX = 0, // 取窗口内的最大值
        PoolMethod_AVE = 1 // 取窗口内的平均值
    };

public:
    // param
    int pooling_type;
    int pyramid_height;
};

} // namespace ncnn

#endif // LAYER_SPP_H
